I have 2 x 2 cylinder diesel Yanmar engines. They are in a catamaran that has been sitting on the hard stand fro 5 years. What do I need to do to before I start them?
HG no doubt will be along to help shortly.
The obvious thing is to check the engine oil first. With the decompression levers engaged, can you turn the engine over by hand?
If the boat is still on the hard you are going to have to organise a cooling water connection.
If you know the model number then owner's manuals are available on the net. Assuming the engines are not seized, first drain the fuel tank and lines, and change filters, oil. Then read the manual and follow the new engine starting procedure.
Replace with new any rubber pump impellers you might have in the raw water cooling system.
Next door neighbour has a Cavalier 36 that he hadn't started for two years or more. He sold the
boat to a friend and they both came down to start it. It fired up OK but the diesel fuel pump rack
had seized open and the engine started and ran at full revs. Fortunately Ross had the presence
of mind to pull the flexible part of the fuel line off and stopped the engine......really scary.
So be aware.
First thing to do is your fuel tank it may have Sam sturdy disease 
It may have need of some biocide in the fuel tank or tanks if there's two tanks
Personally I'd drain the tank and put fresh fuel inland add some biocide
I'd flush the fuel lines up to the filters and replace the fuel filters
Bleed the fuel system
Drain the engine oil replace the filter
If it's not raw water cooled drain the coolant and after inspecting the water pump impeller after its drained
Also check the gearboxes or sail drive read the manual if it has sail drives
Before starting it I'd make a mess and cracked open the injector fuel lines and then wind the motor over
Doing that will give you two positives
One fresh fuel right through the system
Two would winding it over you will be getting oil pressure before it will be started
Select to expand quotesamsturdy said..
Next door neighbour has a Cavalier 36 that he hadn't started for two years or more. He sold the
boat to a friend and they both came down to start it. It fired up OK but the diesel fuel pump rack
had seized open and the engine started and ran at full revs. Fortunately Ross had the presence
of mind to pull the flexible part of the fuel line off and stopped the engine......really scary.
So be aware.
What's already been said above plus if you're a bit mechanically minded I would pull the injector pump apart & clean it. It will most likely be full of "gunk". Do the lift pump as well.
It's not hard, just remember how you pulled it apart, take pics, & you should be able to reassemble it no worries.
I had to do this with mine before I fired it up. Look online for a PDF manual if you don't have one - you'll need it for future reference anyway.
If the engine is sea water cooled I'd drain the engine block refit the drain plug and pour in some vinegar for a few days
Select to expand quoteLazzarae said..samsturdy said..
Next door neighbour has a Cavalier 36 that he hadn't started for two years or more. He sold the
boat to a friend and they both came down to start it. It fired up OK but the diesel fuel pump rack
had seized open and the engine started and ran at full revs. Fortunately Ross had the presence
of mind to pull the flexible part of the fuel line off and stopped the engine......really scary.
So be aware.
What's already been said above plus if you're a bit mechanically minded I would pull the injector pump apart & clean it. It will most likely be full of "gunk". Do the lift pump as well.
It's not hard, just remember how you pulled it apart, take pics, & you should be able to reassemble it no worries.
I had to do this with mine before I fired it up. Look online for a PDF manual if you don't have one - you'll need it for future reference anyway.
Just be aware that in some Yanmars the fuel rack is part of the injector fuel line at the base of the injector pump if the fitting is turned at the base your fuel pump will need to be removed and retested as far as fuel volume to every injector is concerned you will see two fuel nut fittings the base one must never be moved the fuel line nut on top is OK to remove if needed.
The above info is from Yanmar excavators not Yanmar marine but Id say they will be similar motors if not the same in most models other than the marine cooling addons
Lazza talking about other diesel motors
Thanks for the advice, I am prepared for the expense, just do not want to compound it by stupidity. Good advice here. Cheers.
When the motor has sat for a while, condensation remaining in the cylinders can cause some surface rusting of the bore. This happened to one of my motors, which wouldn't turn over. I took out all the injectors and squirted some machine oil into each cylinder and carefully rocked the crank back and forth a little each day. It took a few weeks but the motor freed eventually turned.
As mentioned earlier, when you are ready to start it, turn it over on the starter enough to build up oil pressure.
